The Effect of Arm Support On Upper Extremity Muscle Load In Mexican Adults Performing An Assembly Task

Gabriel Ibarra-Mejia, University of Texas at El Paso


Complaints of musculoskeletal pain and discomfort from workers of a local manufacturing company, lead to study the effect on muscular activity at the shoulder and neck when performing an assembly task in Juarez, Mexico. A mock-up of the work station and task were developed; muscle load activity was measured using surface electromyography (SMEG) at the shoulder (deltoideus) and neck (trapezius) muscles while performing the assembly task without arm support, and using two different types of arm supports. SEMG signals were analyzed to estimate Root Mean Squares (RMS) and Median Frequency (MF). Subjective measures of Rate of Perceived Exertion (RPE), discomfort, and preference rating measures were also assessed. Results showed lower muscular activity when using arm supports. No statistically significant effects were detected in RPE, discomfort, and preference of use. Introducing the use of arm supports in light industrial assembly jobs in Mexico may aid in decreasing the incidence of work related MSDs of the upper extremity.